1. Field of the Invention
The present invention relates to a content-information-management system, a content-information-management apparatus, a content-information-management method, and a computer program that are adapted to manage information relating to usable contents on a home network having a content-reproduce device configured to reproduce and output audio-and-visual (AV) contents, such as a monitor display and a sonic-reproduction device, at least one content-provide device configured to receive broadcast contents, such as a tuner and a CD-and-DVD player, and a content-record device configured to record externally transmitted contents, and particularly relates to a content-information-management system, a content-information-management apparatus, a content-information-management method, and a computer program that are adapted to achieve a list function relating to contents provided by the at least one content-provide device on the home network.
More specifically, the present invention relates to a content-information-management system, a content-information-management apparatus, a content-information-management method, and a computer program that achieve the function of providing first information which is used by a content-use device configured to use contents provided on the home network, so as to obtain desired contents, and particularly relates to a content-information-management system, a content-information-management apparatus, a content-information-management method, and a computer program which provide first information used by the content-use device, so as to obtain desired contents irrespective of the state of the content-provide device storing the desired contents.
2. Description of the Related Art
Recently, various types of AV devices including a TV receiver, a video recording-and-reproducing device, and so forth are developed and manufactured, and widely used in households and/or other living spaces. Each of the above-described AV devices operates, as a content-provide device which provides contents acquired via a transportable medium including a compact disk (CD), a digital versatile disk (DVD), and so forth, or contents received by using a broadcast wave selected by performing tuning. In another case, each of the AV devices operates, as a content-reproduce device configured to output and produce contents including image data and/or speech data, the contents being provided by the content-provide device, as an image and/or speech.
Further, as the information-communication technology progresses, home networks adapted to connect home-information appliances to one another are increasingly used in many households. By using the home network, a user is allowed to enjoy contents provided by an arbitrary content-provide device via a content-reproduce device installed in a desired room.
At present, increasing numbers of digital contents of various types are available. Subsequently, it is expected that the demand for obtaining the digital contents through a personal computer (PC), a mobile device, an AV device, and so forth, and enjoying the contents will increase. For example, Digital Network Living Alliance (DLNA) proposes a network configured to connect electronic devices, for example, to one another seamlessly so that a user can enjoy contents at any place in a house and through any electronic device easily and conveniently. According to the configuration of the network, data such as AV contents may be stored in any device on the network. Subsequently, the user can enjoy contents irrespective of the place where the contents are stored. For example, the user can enjoy contents stored in a device installed in a room some distance from the user's room, which is highly convenient for the user.
It is expected that increasing numbers of DLNA-capable devices will become available and network-capable AV devices will be widely used. If the network-capable devices increases, it becomes possible to perform remote-control operations for the AV devices by using an IP network under a weak constraint relating to directivity and/or a communication area, although remote control for the AV devices were performed by using infrared communications in the past. The above-described DLNA-related technology is disclosed in Japanese Patent Application No. 2005-17435, for example. According to the above-described IP remote-control system, bidirectional communications can be performed between an IP-remote controller and an AV device for control. Therefore, it becomes possible to perform communications with stability by transmitting a transmission-confirmation signal, operating a sophisticated command system by performing graphical-user-interface (GUI) operations, and perform high-capacity data transmission such as video streaming by using a relatively large frequency band.
Thus, the DLNA technology allows for connecting a plurality of network-capable AV devices which provides digital contents of various types to one another so that the user can use the AV devices on the home network. Further, the DLNA technology presents the list function which allows the user to see contents stored in each of the content-provide devices provided on a DLNA network, as if the contents were stored in a single device. Subsequently, the user can enjoy desired contents immediately without being worried about where the contents really are.
Usually, a user turns off the power of an electronic device which is not used and turns on the power when the user wants to use the electronic device. Recently, the above-described power control is particularly important in view of socioecology which proposes the concept of resource finiteness. However, when the power of an AV device is turned off, it is difficult for the user to refer to contents provided by the above-described AV device with its power turned off via a network. Thus, the above-described known technology does not allow the user to see all the contents provided on the home network at a glance.
If all the contents provided by the AV devices installed on the home network are stored in a predetermined content-provide server, the user can see all the contents at a glance through the content-provide server even after the power of each of other AV devices is turned off, for example.
However, since the content-provide server is expensive, the cost of performing the above-described method of unitarily controlling all the contents by using the content-provide server increases. Further, the use of the content-provide server puts the entire system under restraint when an AV device which provides contents is added and/or contents provided to the user are added. Namely, the flexibility of the entire system decreases due to the use of the content-provide server.
There have been proposed methods for managing contents on the basis of identification information of the contents stored in the content-provide server. One of the above-described methods is disclosed in Japanese Unexamined Patent Application Publication No. 2004-234158, for example. In that case, the content-provide server determines the unique-identifier information corresponding to the contents to be an element of the meta data corresponding to the contents, and sets the element, as property information. Although the contents stored in a storage unit is physically changed, or the position where the contents are stored is physically changed, the content-provide server maintains the unique-identifier information, as the meta data corresponding to the contents, and manages the unique-identifier information, as the meta data corresponding to transmitted contents without changing the value of the unique-identifier information which is set, so as to correspond to the transmitted contents. According to the above-described configuration, it becomes possible for a client to acquire contents on the basis of unique-identifier information, even though the contents are moved between at least two servers.